Mauritania criminalised slavery in 2015. In past cases, slave-owners were sentenced to two to five years.

Rights group Amnesty International welcomed the convictions. It estimates that 43,000 people were still living in slavery in Mauritania.

It said that the courts had received 47 cases for investigation involving 53 suspects.

However prominent Mauritanian anti-slavery activist Biram Ould Dah Abeid cast doubt on the reports that Hamoudi Ould Saleck had actually been arrested, and called the case "a show trial by the government to stop criticism from the international community".

Earlier this year, the African Union urged Mauritania to issue harsher sentences for the crime.